10.3389/fchem.2019.00413.s001
Angela Capocefalo
Angela
Capocefalo
Daisy Mammucari
Daisy
Mammucari
Francesco Brasili
Francesco
Brasili
Claudia Fasolato
Claudia
Fasolato
Federico Bordi
Federico
Bordi
Paolo Postorino
Paolo
Postorino
Fabio Domenici
Fabio
Domenici
Data_Sheet_1_Exploring the Potentiality of a SERS-Active pH Nano-Biosensor.PDF
Frontiers
2019
SERS
pH sensor
plasmonics
gold nanoparticles
biosensing
extracellular pH
cancer cells
2019-06-07 13:39:15
Dataset
https://frontiersin.figshare.com/articles/dataset/Data_Sheet_1_Exploring_the_Potentiality_of_a_SERS-Active_pH_Nano-Biosensor_PDF/8242562
<p>The merging of the molecular specificity of Raman spectroscopy with the extraordinary optical properties of metallic nanoarchitectures is at the heart of Surface Enhanced Raman Spectroscopy (SERS), which in the last few decades proved its worth as powerful analytical tool with detection limits pushed to the single molecule recognition. Within this frame, SERS-based nanosensors for localized pH measurements have been developed and employed for a wide range of applications. Nevertheless, to improve the performances of such nanosensors, many key issues concerning their assembling, calibration and stability, that could significantly impact on the outcome of the pH measurements, need to be clarified. Here, we report on the detailed characterization of a case study SERS-active pH nanosensor, based on the conjugation of gold nanoparticles with the pH-sensitive molecular probe 4-mercaptobenzoic acid (4MBA). We analyzed and optimized all the aspects of the synthesis procedure and of the operating conditions to preserve the sensor stability and provide the highest responsiveness to pH. Exploiting the dependence of the SERS spectrum on the protonation degree of the carboxylic group at the edge of the 4MBA molecules, we derived a calibration curve for the nanosensor. The extrapolated working point, i.e., the pH value corresponding to the highest sensitivity, falls at pH 5.6, which corresponds to the pKa value of the molecule confined at the nanoparticle surface. A shift of the pKa of 4MBA, observed on the molecules confined at the nanostructured interface respect to the bulk counterpart, unveils the opportunity to assembly a SERS-based pH nanosensor with the ability to select its working point in the sensitivity region of interest, by acting on the nanostructured surface on which the molecular probe is confined. As a proof-of-concept, the nanosensor was successfully employed to measure the extracellular pH of normal and cancer cells, demonstrating the capability to discriminate between them.</p>